#![feature(box_patterns)] #![feature(control_flow_enum)] #![feature(let_else)] #![feature(let_chains)] #![feature(lint_reasons)] #![feature(once_cell)] #![feature(rustc_private)] #![recursion_limit = "512"] #![cfg_attr(feature = "deny-warnings", deny(warnings))] #![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)] // warn on the same lints as `clippy_lints` #![warn(trivial_casts, trivial_numeric_casts)] // warn on lints, that are included in `rust-lang/rust`s bootstrap #![warn(rust_2018_idioms, unused_lifetimes)] // warn on rustc internal lints #![warn(rustc::internal)] // FIXME: switch to something more ergonomic here, once available. // (Currently there is no way to opt into sysroot crates without `extern crate`.) extern crate rustc_ast; extern crate rustc_ast_pretty; extern crate rustc_attr; extern crate rustc_data_structures; extern crate rustc_errors; extern crate rustc_hir; extern crate rustc_infer; extern crate rustc_lexer; extern crate rustc_lint; extern crate rustc_middle; extern crate rustc_session; extern crate rustc_span; extern crate rustc_target; extern crate rustc_trait_selection; extern crate rustc_typeck; #[macro_use] pub mod sym_helper; pub mod ast_utils; pub mod attrs; pub mod comparisons; pub mod consts; pub mod diagnostics; pub mod eager_or_lazy; pub mod higher; mod hir_utils; pub mod macros; pub mod msrvs; pub mod numeric_literal; pub mod paths; pub mod ptr; pub mod qualify_min_const_fn; pub mod source; pub mod str_utils; pub mod sugg; pub mod ty; pub mod usage; pub mod visitors; pub use self::attrs::*; pub use self::hir_utils::{ both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash, }; use std::collections::hash_map::Entry; use std::hash::BuildHasherDefault; use std::sync::OnceLock; use std::sync::{Mutex, MutexGuard}; use if_chain::if_chain; use rustc_ast::ast::{self, LitKind}; use rustc_ast::Attribute; use rustc_data_structures::fx::FxHashMap; use rustc_data_structures::unhash::UnhashMap; use rustc_hir as hir; use rustc_hir::def::{DefKind, Res}; use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_ID}; use rustc_hir::hir_id::{HirIdMap, HirIdSet}; use rustc_hir::intravisit::{walk_expr, FnKind, Visitor}; use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk}; use rustc_hir::{ def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Constness, Destination, Expr, ExprKind, FnDecl, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp, }; use rustc_lint::{LateContext, Level, Lint, LintContext}; use rustc_middle::hir::place::PlaceBase; use rustc_middle::ty as rustc_ty; use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow}; use rustc_middle::ty::binding::BindingMode; use rustc_middle::ty::fast_reject::SimplifiedTypeGen::{ ArraySimplifiedType, BoolSimplifiedType, CharSimplifiedType, FloatSimplifiedType, IntSimplifiedType, PtrSimplifiedType, SliceSimplifiedType, StrSimplifiedType, UintSimplifiedType, }; use rustc_middle::ty::{layout::IntegerExt, BorrowKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeVisitable, UpvarCapture}; use rustc_middle::ty::{FloatTy, IntTy, UintTy}; use rustc_semver::RustcVersion; use rustc_session::Session; use rustc_span::hygiene::{ExpnKind, MacroKind}; use rustc_span::source_map::original_sp; use rustc_span::sym; use rustc_span::symbol::{kw, Symbol}; use rustc_span::{Span, DUMMY_SP}; use rustc_target::abi::Integer; use crate::consts::{constant, Constant}; use crate::ty::{can_partially_move_ty, is_copy, is_recursively_primitive_type}; use crate::visitors::expr_visitor_no_bodies; pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option) -> Option { if let Ok(version) = RustcVersion::parse(msrv) { return Some(version); } else if let Some(sess) = sess { if let Some(span) = span { sess.span_err(span, &format!("`{}` is not a valid Rust version", msrv)); } } None } pub fn meets_msrv(msrv: Option, lint_msrv: RustcVersion) -> bool { msrv.map_or(true, |msrv| msrv.meets(lint_msrv)) } #[macro_export] macro_rules! extract_msrv_attr { ($context:ident) => { fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) { let sess = rustc_lint::LintContext::sess(cx); match $crate::get_unique_inner_attr(sess, attrs, "msrv") { Some(msrv_attr) => { if let Some(msrv) = msrv_attr.value_str() { self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span)); } else { sess.span_err(msrv_attr.span, "bad clippy attribute"); } }, _ => (), } } }; } /// If the given expression is a local binding, find the initializer expression. /// If that initializer expression is another local binding, find its initializer again. /// This process repeats as long as possible (but usually no more than once). Initializer /// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`] /// instead. /// /// Examples: /// ``` /// let abc = 1; /// // ^ output /// let def = abc; /// dbg!(def); /// // ^^^ input /// /// // or... /// let abc = 1; /// let def = abc + 2; /// // ^^^^^^^ output /// dbg!(def); /// // ^^^ input /// ``` pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> { while let Some(init) = path_to_local(expr) .and_then(|id| find_binding_init(cx, id)) .filter(|init| cx.typeck_results().expr_adjustments(init).is_empty()) { expr = init; } expr } /// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable. /// By only considering immutable bindings, we guarantee that the returned expression represents the /// value of the binding wherever it is referenced. /// /// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned. /// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the /// canonical binding `HirId`. pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> { let hir = cx.tcx.hir(); if_chain! { if let Some(Node::Pat(pat)) = hir.find(hir_id); if matches!(pat.kind, PatKind::Binding(BindingAnnotation::Unannotated, ..)); let parent = hir.get_parent_node(hir_id); if let Some(Node::Local(local)) = hir.find(parent); then { return local.init; } } None } /// Returns `true` if the given `NodeId` is inside a constant context /// /// # Example /// /// ```rust,ignore /// if in_constant(cx, expr.hir_id) { /// // Do something /// } /// ``` pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool { let parent_id = cx.tcx.hir().get_parent_item(id); match cx.tcx.hir().get_by_def_id(parent_id) { Node::Item(&Item { kind: ItemKind::Const(..) | ItemKind::Static(..), .. }) | Node::TraitItem(&TraitItem { kind: TraitItemKind::Const(..), .. }) | Node::ImplItem(&ImplItem { kind: ImplItemKind::Const(..), .. }) | Node::AnonConst(_) => true, Node::Item(&Item { kind: ItemKind::Fn(ref sig, ..), .. }) | Node::ImplItem(&ImplItem { kind: ImplItemKind::Fn(ref sig, _), .. }) => sig.header.constness == Constness::Const, _ => false, } } /// Checks if a `QPath` resolves to a constructor of a `LangItem`. /// For example, use this to check whether a function call or a pattern is `Some(..)`. pub fn is_lang_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, lang_item: LangItem) -> bool { if let QPath::Resolved(_, path) = qpath { if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res { if let Ok(item_id) = cx.tcx.lang_items().require(lang_item) { return cx.tcx.parent(ctor_id) == item_id; } } } false } pub fn is_unit_expr(expr: &Expr<'_>) -> bool { matches!( expr.kind, ExprKind::Block( Block { stmts: [], expr: None, .. }, _ ) | ExprKind::Tup([]) ) } /// Checks if given pattern is a wildcard (`_`) pub fn is_wild(pat: &Pat<'_>) -> bool { matches!(pat.kind, PatKind::Wild) } /// Checks if the method call given in `expr` belongs to the given trait. /// This is a deprecated function, consider using [`is_trait_method`]. pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool { let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap(); let trt_id = cx.tcx.trait_of_item(def_id); trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path)) } /// Checks if a method is defined in an impl of a diagnostic item pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool { if let Some(impl_did) = cx.tcx.impl_of_method(def_id) { if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() { return cx.tcx.is_diagnostic_item(diag_item, adt.did()); } } false } /// Checks if a method is in a diagnostic item trait pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool { if let Some(trait_did) = cx.tcx.trait_of_item(def_id) { return cx.tcx.is_diagnostic_item(diag_item, trait_did); } false } /// Checks if the method call given in `expr` belongs to the given trait. pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool { cx.typeck_results() .type_dependent_def_id(expr.hir_id) .map_or(false, |did| is_diag_trait_item(cx, did, diag_item)) } /// Checks if the given expression is a path referring an item on the trait /// that is marked with the given diagnostic item. /// /// For checking method call expressions instead of path expressions, use /// [`is_trait_method`]. /// /// For example, this can be used to find if an expression like `u64::default` /// refers to an item of the trait `Default`, which is associated with the /// `diag_item` of `sym::Default`. pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool { if let hir::ExprKind::Path(ref qpath) = expr.kind { cx.qpath_res(qpath, expr.hir_id) .opt_def_id() .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item)) } else { false } } pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> { match *path { QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"), QPath::TypeRelative(_, seg) => seg, QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"), } } pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator> { last_path_segment(qpath) .args .map_or(&[][..], |a| a.args) .iter() .filter_map(|a| match a { hir::GenericArg::Type(ty) => Some(ty), _ => None, }) } /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from /// `QPath::Resolved.1.res.opt_def_id()`. /// /// Matches a `QPath` against a slice of segment string literals. /// /// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a /// `rustc_hir::QPath`. /// /// # Examples /// ```rust,ignore /// match_qpath(path, &["std", "rt", "begin_unwind"]) /// ``` pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool { match *path { QPath::Resolved(_, path) => match_path(path, segments), QPath::TypeRelative(ty, segment) => match ty.kind { TyKind::Path(ref inner_path) => { if let [prefix @ .., end] = segments { if match_qpath(inner_path, prefix) { return segment.ident.name.as_str() == *end; } } false }, _ => false, }, QPath::LangItem(..) => false, } } /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path. /// /// Please use `is_expr_diagnostic_item` if the target is a diagnostic item. pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool { path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, segments)) } /// If the expression is a path, resolves it to a `DefId` and checks if it matches the given /// diagnostic item. pub fn is_expr_diagnostic_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool { path_def_id(cx, expr).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id)) } /// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the /// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from /// `QPath::Resolved.1.res.opt_def_id()`. /// /// Matches a `Path` against a slice of segment string literals. /// /// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a /// `rustc_hir::Path`. /// /// # Examples /// /// ```rust,ignore /// if match_path(&trait_ref.path, &paths::HASH) { /// // This is the `std::hash::Hash` trait. /// } /// /// if match_path(ty_path, &["rustc", "lint", "Lint"]) { /// // This is a `rustc_middle::lint::Lint`. /// } /// ``` pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool { path.segments .iter() .rev() .zip(segments.iter().rev()) .all(|(a, b)| a.ident.name.as_str() == *b) } /// If the expression is a path to a local, returns the canonical `HirId` of the local. pub fn path_to_local(expr: &Expr<'_>) -> Option { if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind { if let Res::Local(id) = path.res { return Some(id); } } None } /// Returns true if the expression is a path to a local with the specified `HirId`. /// Use this function to see if an expression matches a function argument or a match binding. pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool { path_to_local(expr) == Some(id) } pub trait MaybePath<'hir> { fn hir_id(&self) -> HirId; fn qpath_opt(&self) -> Option<&QPath<'hir>>; } macro_rules! maybe_path { ($ty:ident, $kind:ident) => { impl<'hir> MaybePath<'hir> for hir::$ty<'hir> { fn hir_id(&self) -> HirId { self.hir_id } fn qpath_opt(&self) -> Option<&QPath<'hir>> { match &self.kind { hir::$kind::Path(qpath) => Some(qpath), _ => None, } } } }; } maybe_path!(Expr, ExprKind); maybe_path!(Pat, PatKind); maybe_path!(Ty, TyKind); /// If `maybe_path` is a path node, resolves it, otherwise returns `Res::Err` pub fn path_res<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Res { match maybe_path.qpath_opt() { None => Res::Err, Some(qpath) => cx.qpath_res(qpath, maybe_path.hir_id()), } } /// If `maybe_path` is a path node which resolves to an item, retrieves the item ID pub fn path_def_id<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Option { path_res(cx, maybe_path).opt_def_id() } /// Resolves a def path like `std::vec::Vec`. /// This function is expensive and should be used sparingly. pub fn def_path_res(cx: &LateContext<'_>, path: &[&str]) -> Res { fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str) -> Option { match tcx.def_kind(def_id) { DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx .module_children(def_id) .iter() .find(|item| item.ident.name.as_str() == name) .map(|child| child.res.expect_non_local()), DefKind::Impl => tcx .associated_item_def_ids(def_id) .iter() .copied() .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name) .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)), _ => None, } } fn find_primitive<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator + 'tcx { let single = |ty| tcx.incoherent_impls(ty).iter().copied(); let empty = || [].iter().copied(); match name { "bool" => single(BoolSimplifiedType), "char" => single(CharSimplifiedType), "str" => single(StrSimplifiedType), "array" => single(ArraySimplifiedType), "slice" => single(SliceSimplifiedType), // FIXME: rustdoc documents these two using just `pointer`. // // Maybe this is something we should do here too. "const_ptr" => single(PtrSimplifiedType(Mutability::Not)), "mut_ptr" => single(PtrSimplifiedType(Mutability::Mut)), "isize" => single(IntSimplifiedType(IntTy::Isize)), "i8" => single(IntSimplifiedType(IntTy::I8)), "i16" => single(IntSimplifiedType(IntTy::I16)), "i32" => single(IntSimplifiedType(IntTy::I32)), "i64" => single(IntSimplifiedType(IntTy::I64)), "i128" => single(IntSimplifiedType(IntTy::I128)), "usize" => single(UintSimplifiedType(UintTy::Usize)), "u8" => single(UintSimplifiedType(UintTy::U8)), "u16" => single(UintSimplifiedType(UintTy::U16)), "u32" => single(UintSimplifiedType(UintTy::U32)), "u64" => single(UintSimplifiedType(UintTy::U64)), "u128" => single(UintSimplifiedType(UintTy::U128)), "f32" => single(FloatSimplifiedType(FloatTy::F32)), "f64" => single(FloatSimplifiedType(FloatTy::F64)), _ => empty(), } } fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option { tcx.crates(()) .iter() .copied() .find(|&num| tcx.crate_name(num).as_str() == name) .map(CrateNum::as_def_id) } let (base, first, path) = match *path { [base, first, ref path @ ..] => (base, first, path), [primitive] => { return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy); }, _ => return Res::Err, }; let tcx = cx.tcx; let starts = find_primitive(tcx, base) .chain(find_crate(tcx, base)) .filter_map(|id| item_child_by_name(tcx, id, first)); for first in starts { let last = path .iter() .copied() // for each segment, find the child item .try_fold(first, |res, segment| { let def_id = res.def_id(); if let Some(item) = item_child_by_name(tcx, def_id, segment) { Some(item) } else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) { // it is not a child item so check inherent impl items tcx.inherent_impls(def_id) .iter() .find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment)) } else { None } }); if let Some(last) = last { return last; } } Res::Err } /// Convenience function to get the `DefId` of a trait by path. /// It could be a trait or trait alias. pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option { match def_path_res(cx, path) { Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id), _ => None, } } /// Gets the `hir::TraitRef` of the trait the given method is implemented for. /// /// Use this if you want to find the `TraitRef` of the `Add` trait in this example: /// /// ```rust /// struct Point(isize, isize); /// /// impl std::ops::Add for Point { /// type Output = Self; /// /// fn add(self, other: Self) -> Self { /// Point(0, 0) /// } /// } /// ``` pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> { // Get the implemented trait for the current function let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id); let parent_impl = cx.tcx.hir().get_parent_item(hir_id); if_chain! { if parent_impl != CRATE_DEF_ID; if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl); if let hir::ItemKind::Impl(impl_) = &item.kind; then { return impl_.of_trait.as_ref(); } } None } /// This method will return tuple of projection stack and root of the expression, /// used in `can_mut_borrow_both`. /// /// For example, if `e` represents the `v[0].a.b[x]` /// this method will return a tuple, composed of a `Vec` /// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]` /// and an `Expr` for root of them, `v` fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) { let mut result = vec![]; let root = loop { match e.kind { ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => { result.push(e); e = ep; }, _ => break e, }; }; result.reverse(); (result, root) } /// Gets the mutability of the custom deref adjustment, if any. pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option { cx.typeck_results() .expr_adjustments(e) .iter() .find_map(|a| match a.kind { Adjust::Deref(Some(d)) => Some(Some(d.mutbl)), Adjust::Deref(None) => None, _ => Some(None), }) .and_then(|x| x) } /// Checks if two expressions can be mutably borrowed simultaneously /// and they aren't dependent on borrowing same thing twice pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool { let (s1, r1) = projection_stack(e1); let (s2, r2) = projection_stack(e2); if !eq_expr_value(cx, r1, r2) { return true; } if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() { return false; } for (x1, x2) in s1.iter().zip(s2.iter()) { if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() { return false; } match (&x1.kind, &x2.kind) { (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => { if i1 != i2 { return true; } }, (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => { if !eq_expr_value(cx, i1, i2) { return false; } }, _ => return false, } } false } /// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent" /// constructor from the std library fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool { let std_types_symbols = &[ sym::String, sym::Vec, sym::VecDeque, sym::LinkedList, sym::HashMap, sym::BTreeMap, sym::HashSet, sym::BTreeSet, sym::BinaryHeap, ]; if let QPath::TypeRelative(_, method) = path { if method.ident.name == sym::new { if let Some(impl_did) = cx.tcx.impl_of_method(def_id) { if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() { return std_types_symbols .iter() .any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did())); } } } } false } /// Return true if the expr is equal to `Default::default` when evaluated. pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool { if_chain! { if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind; if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id(); if is_diag_trait_item(cx, repl_def_id, sym::Default) || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath); then { true } else { false } } } /// Returns true if the expr is equal to `Default::default()` of it's type when evaluated. /// It doesn't cover all cases, for example indirect function calls (some of std /// functions are supported) but it is the best we have. pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool { match &e.kind { ExprKind::Lit(lit) => match lit.node { LitKind::Bool(false) | LitKind::Int(0, _) => true, LitKind::Str(s, _) => s.is_empty(), _ => false, }, ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)), ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! { if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind; if let LitKind::Int(v, _) = const_lit.node; if v <= 32 && is_default_equivalent(cx, x); then { true } else { false } }, ExprKind::Call(repl_func, _) => is_default_equivalent_call(cx, repl_func), ExprKind::Path(qpath) => is_lang_ctor(cx, qpath, OptionNone), ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])), _ => false, } } /// Checks if the top level expression can be moved into a closure as is. /// Currently checks for: /// * Break/Continue outside the given loop HIR ids. /// * Yield/Return statements. /// * Inline assembly. /// * Usages of a field of a local where the type of the local can be partially moved. /// /// For example, given the following function: /// /// ``` /// fn f<'a>(iter: &mut impl Iterator) { /// for item in iter { /// let s = item.1; /// if item.0 > 10 { /// continue; /// } else { /// s.clear(); /// } /// } /// } /// ``` /// /// When called on the expression `item.0` this will return false unless the local `item` is in the /// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it /// isn't always safe to move into a closure when only a single field is needed. /// /// When called on the `continue` expression this will return false unless the outer loop expression /// is in the `loop_ids` set. /// /// Note that this check is not recursive, so passing the `if` expression will always return true /// even though sub-expressions might return false. pub fn can_move_expr_to_closure_no_visit<'tcx>( cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, loop_ids: &[HirId], ignore_locals: &HirIdSet, ) -> bool { match expr.kind { ExprKind::Break(Destination { target_id: Ok(id), .. }, _) | ExprKind::Continue(Destination { target_id: Ok(id), .. }) if loop_ids.contains(&id) => { true }, ExprKind::Break(..) | ExprKind::Continue(_) | ExprKind::Ret(_) | ExprKind::Yield(..) | ExprKind::InlineAsm(_) => false, // Accessing a field of a local value can only be done if the type isn't // partially moved. ExprKind::Field( &Expr { hir_id, kind: ExprKind::Path(QPath::Resolved( _, Path { res: Res::Local(local_id), .. }, )), .. }, _, ) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => { // TODO: check if the local has been partially moved. Assume it has for now. false }, _ => true, } } /// How a local is captured by a closure #[derive(Debug, Clone, Copy, PartialEq, Eq)] pub enum CaptureKind { Value, Ref(Mutability), } impl CaptureKind { pub fn is_imm_ref(self) -> bool { self == Self::Ref(Mutability::Not) } } impl std::ops::BitOr for CaptureKind { type Output = Self; fn bitor(self, rhs: Self) -> Self::Output { match (self, rhs) { (CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value, (CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_)) | (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut), (CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not), } } } impl std::ops::BitOrAssign for CaptureKind { fn bitor_assign(&mut self, rhs: Self) { *self = *self | rhs; } } /// Given an expression referencing a local, determines how it would be captured in a closure. /// Note as this will walk up to parent expressions until the capture can be determined it should /// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or /// function argument (other than a receiver). pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind { fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind { let mut capture = CaptureKind::Ref(Mutability::Not); pat.each_binding_or_first(&mut |_, id, span, _| match cx .typeck_results() .extract_binding_mode(cx.sess(), id, span) .unwrap() { BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => { capture = CaptureKind::Value; }, BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => { capture = CaptureKind::Ref(Mutability::Mut); }, _ => (), }); capture } debug_assert!(matches!( e.kind, ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. })) )); let mut child_id = e.hir_id; let mut capture = CaptureKind::Value; let mut capture_expr_ty = e; for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) { if let [ Adjustment { kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)), target, }, ref adjust @ .., ] = *cx .typeck_results() .adjustments() .get(child_id) .map_or(&[][..], |x| &**x) { if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) = *adjust.last().map_or(target, |a| a.target).kind() { return CaptureKind::Ref(mutability); } } match parent { Node::Expr(e) => match e.kind { ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability), ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not), ExprKind::Assign(lhs, ..) | ExprKind::Assign(_, lhs, _) if lhs.hir_id == child_id => { return CaptureKind::Ref(Mutability::Mut); }, ExprKind::Field(..) => { if capture == CaptureKind::Value { capture_expr_ty = e; } }, ExprKind::Let(let_expr) => { let mutability = match pat_capture_kind(cx, let_expr.pat) { CaptureKind::Value => Mutability::Not, CaptureKind::Ref(m) => m, }; return CaptureKind::Ref(mutability); }, ExprKind::Match(_, arms, _) => { let mut mutability = Mutability::Not; for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) { match capture { CaptureKind::Value => break, CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut, CaptureKind::Ref(Mutability::Not) => (), } } return CaptureKind::Ref(mutability); }, _ => break, }, Node::Local(l) => match pat_capture_kind(cx, l.pat) { CaptureKind::Value => break, capture @ CaptureKind::Ref(_) => return capture, }, _ => break, } child_id = parent_id; } if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) { // Copy types are never automatically captured by value. CaptureKind::Ref(Mutability::Not) } else { capture } } /// Checks if the expression can be moved into a closure as is. This will return a list of captures /// if so, otherwise, `None`. pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option> { struct V<'cx, 'tcx> { cx: &'cx LateContext<'tcx>, // Stack of potential break targets contained in the expression. loops: Vec, /// Local variables created in the expression. These don't need to be captured. locals: HirIdSet, /// Whether this expression can be turned into a closure. allow_closure: bool, /// Locals which need to be captured, and whether they need to be by value, reference, or /// mutable reference. captures: HirIdMap, } impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> { fn visit_expr(&mut self, e: &'tcx Expr<'_>) { if !self.allow_closure { return; } match e.kind { ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => { if !self.locals.contains(&l) { let cap = capture_local_usage(self.cx, e); self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap); } }, ExprKind::Closure { .. } => { let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id).to_def_id(); for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) { let local_id = match capture.place.base { PlaceBase::Local(id) => id, PlaceBase::Upvar(var) => var.var_path.hir_id, _ => continue, }; if !self.locals.contains(&local_id) { let capture = match capture.info.capture_kind { UpvarCapture::ByValue => CaptureKind::Value, UpvarCapture::ByRef(kind) => match kind { BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not), BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => { CaptureKind::Ref(Mutability::Mut) }, }, }; self.captures .entry(local_id) .and_modify(|e| *e |= capture) .or_insert(capture); } } }, ExprKind::Loop(b, ..) => { self.loops.push(e.hir_id); self.visit_block(b); self.loops.pop(); }, _ => { self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals); walk_expr(self, e); }, } } fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) { p.each_binding_or_first(&mut |_, id, _, _| { self.locals.insert(id); }); } } let mut v = V { cx, allow_closure: true, loops: Vec::new(), locals: HirIdSet::default(), captures: HirIdMap::default(), }; v.visit_expr(expr); v.allow_closure.then(|| v.captures) } /// Returns the method names and argument list of nested method call expressions that make up /// `expr`. method/span lists are sorted with the most recent call first. pub fn method_calls<'tcx>( expr: &'tcx Expr<'tcx>, max_depth: usize, ) -> (Vec, Vec<&'tcx [Expr<'tcx>]>, Vec) { let mut method_names = Vec::with_capacity(max_depth); let mut arg_lists = Vec::with_capacity(max_depth); let mut spans = Vec::with_capacity(max_depth); let mut current = expr; for _ in 0..max_depth { if let ExprKind::MethodCall(path, args, _) = ¤t.kind { if args.iter().any(|e| e.span.from_expansion()) { break; } method_names.push(path.ident.name); arg_lists.push(&**args); spans.push(path.ident.span); current = &args[0]; } else { break; } } (method_names, arg_lists, spans) } /// Matches an `Expr` against a chain of methods, and return the matched `Expr`s. /// /// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`, /// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec` /// containing the `Expr`s for /// `.bar()` and `.baz()` pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option]>> { let mut current = expr; let mut matched = Vec::with_capacity(methods.len()); for method_name in methods.iter().rev() { // method chains are stored last -> first if let ExprKind::MethodCall(path, args, _) = current.kind { if path.ident.name.as_str() == *method_name { if args.iter().any(|e| e.span.from_expansion()) { return None; } matched.push(args); // build up `matched` backwards current = &args[0]; // go to parent expression } else { return None; } } else { return None; } } // Reverse `matched` so that it is in the same order as `methods`. matched.reverse(); Some(matched) } /// Returns `true` if the provided `def_id` is an entrypoint to a program. pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool { cx.tcx .entry_fn(()) .map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id) } /// Returns `true` if the expression is in the program's `#[panic_handler]`. pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool { let parent = cx.tcx.hir().get_parent_item(e.hir_id); Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl() } /// Gets the name of the item the expression is in, if available. pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option { let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id); match cx.tcx.hir().find_by_def_id(parent_id) { Some( Node::Item(Item { ident, .. }) | Node::TraitItem(TraitItem { ident, .. }) | Node::ImplItem(ImplItem { ident, .. }), ) => Some(ident.name), _ => None, } } pub struct ContainsName { pub name: Symbol, pub result: bool, } impl<'tcx> Visitor<'tcx> for ContainsName { fn visit_name(&mut self, _: Span, name: Symbol) { if self.name == name { self.result = true; } } } /// Checks if an `Expr` contains a certain name. pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool { let mut cn = ContainsName { name, result: false }; cn.visit_expr(expr); cn.result } /// Returns `true` if `expr` contains a return expression pub fn contains_return(expr: &hir::Expr<'_>) -> bool { let mut found = false; expr_visitor_no_bodies(|expr| { if !found { if let hir::ExprKind::Ret(..) = &expr.kind { found = true; } } !found }) .visit_expr(expr); found } /// Extends the span to the beginning of the spans line, incl. whitespaces. /// /// ```rust /// let x = (); /// // ^^ /// // will be converted to /// let x = (); /// // ^^^^^^^^^^^^^^ /// ``` fn line_span(cx: &T, span: Span) -> Span { let span = original_sp(span, DUMMY_SP); let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap(); let line_no = source_map_and_line.line; let line_start = source_map_and_line.sf.lines(|lines| lines[line_no]); span.with_lo(line_start) } /// Gets the parent node, if any. pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option> { tcx.hir().parent_iter(id).next().map(|(_, node)| node) } /// Gets the parent expression, if any –- this is useful to constrain a lint. pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> { get_parent_expr_for_hir(cx, e.hir_id) } /// This retrieves the parent for the given `HirId` if it's an expression. This is useful for /// constraint lints pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> { match get_parent_node(cx.tcx, hir_id) { Some(Node::Expr(parent)) => Some(parent), _ => None, } } pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> { let map = &cx.tcx.hir(); let enclosing_node = map .get_enclosing_scope(hir_id) .and_then(|enclosing_id| map.find(enclosing_id)); enclosing_node.and_then(|node| match node { Node::Block(block) => Some(block), Node::Item(&Item { kind: ItemKind::Fn(_, _, eid), .. }) | Node::ImplItem(&ImplItem { kind: ImplItemKind::Fn(_, eid), .. }) => match cx.tcx.hir().body(eid).value.kind { ExprKind::Block(block, _) => Some(block), _ => None, }, _ => None, }) } /// Gets the loop or closure enclosing the given expression, if any. pub fn get_enclosing_loop_or_closure<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> { for (_, node) in tcx.hir().parent_iter(expr.hir_id) { match node { Node::Expr( e @ Expr { kind: ExprKind::Loop(..) | ExprKind::Closure { .. }, .. }, ) => return Some(e), Node::Expr(_) | Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (), _ => break, } } None } /// Gets the parent node if it's an impl block. pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> { match tcx.hir().parent_iter(id).next() { Some(( _, Node::Item(Item { kind: ItemKind::Impl(imp), .. }), )) => Some(imp), _ => None, } } /// Removes blocks around an expression, only if the block contains just one expression /// and no statements. Unsafe blocks are not removed. /// /// Examples: /// * `{}` -> `{}` /// * `{ x }` -> `x` /// * `{{ x }}` -> `x` /// * `{ x; }` -> `{ x; }` /// * `{ x; y }` -> `{ x; y }` /// * `{ unsafe { x } }` -> `unsafe { x }` pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> { while let ExprKind::Block( Block { stmts: [], expr: Some(inner), rules: BlockCheckMode::DefaultBlock, .. }, _, ) = expr.kind { expr = inner; } expr } /// Removes blocks around an expression, only if the block contains just one expression /// or just one expression statement with a semicolon. Unsafe blocks are not removed. /// /// Examples: /// * `{}` -> `{}` /// * `{ x }` -> `x` /// * `{ x; }` -> `x` /// * `{{ x; }}` -> `x` /// * `{ x; y }` -> `{ x; y }` /// * `{ unsafe { x } }` -> `unsafe { x }` pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> { while let ExprKind::Block( Block { stmts: [], expr: Some(inner), rules: BlockCheckMode::DefaultBlock, .. } | Block { stmts: [ Stmt { kind: StmtKind::Expr(inner) | StmtKind::Semi(inner), .. }, ], expr: None, rules: BlockCheckMode::DefaultBlock, .. }, _, ) = expr.kind { expr = inner; } expr } /// Checks if the given expression is the else clause of either an `if` or `if let` expression. pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool { let mut iter = tcx.hir().parent_iter(expr.hir_id); match iter.next() { Some(( _, Node::Expr(Expr { kind: ExprKind::If(_, _, Some(else_expr)), .. }), )) => else_expr.hir_id == expr.hir_id, _ => false, } } /// Checks whether the given expression is a constant integer of the given value. /// unlike `is_integer_literal`, this version does const folding pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool { if is_integer_literal(e, value) { return true; } let enclosing_body = cx.tcx.hir().local_def_id(cx.tcx.hir().enclosing_body_owner(e.hir_id)); if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) { return value == v; } false } /// Checks whether the given expression is a constant literal of the given value. pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool { // FIXME: use constant folding if let ExprKind::Lit(ref spanned) = expr.kind { if let LitKind::Int(v, _) = spanned.node { return v == value; } } false } /// Returns `true` if the given `Expr` has been coerced before. /// /// Examples of coercions can be found in the Nomicon at /// . /// /// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_typeck::check::coercion` for more /// information on adjustments and coercions. pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool { cx.typeck_results().adjustments().get(e.hir_id).is_some() } /// Returns the pre-expansion span if this comes from an expansion of the /// macro `name`. /// See also [`is_direct_expn_of`]. #[must_use] pub fn is_expn_of(mut span: Span, name: &str) -> Option { loop { if span.from_expansion() { let data = span.ctxt().outer_expn_data(); let new_span = data.call_site; if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind { if mac_name.as_str() == name { return Some(new_span); } } span = new_span; } else { return None; } } } /// Returns the pre-expansion span if the span directly comes from an expansion /// of the macro `name`. /// The difference with [`is_expn_of`] is that in /// ```rust /// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } } /// # macro_rules! bar { ($e:expr) => { $e } } /// foo!(bar!(42)); /// ``` /// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only /// from `bar!` by `is_direct_expn_of`. #[must_use] pub fn is_direct_expn_of(span: Span, name: &str) -> Option { if span.from_expansion() { let data = span.ctxt().outer_expn_data(); let new_span = data.call_site; if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind { if mac_name.as_str() == name { return Some(new_span); } } } None } /// Convenience function to get the return type of a function. pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> { let fn_def_id = cx.tcx.hir().local_def_id(fn_item); let ret_ty = cx.tcx.fn_sig(fn_def_id).output(); cx.tcx.erase_late_bound_regions(ret_ty) } /// Convenience function to get the nth argument type of a function. pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> { let fn_def_id = cx.tcx.hir().local_def_id(fn_item); let arg = cx.tcx.fn_sig(fn_def_id).input(nth); cx.tcx.erase_late_bound_regions(arg) } /// Checks if an expression is constructing a tuple-like enum variant or struct pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { if let ExprKind::Call(fun, _) = expr.kind { if let ExprKind::Path(ref qp) = fun.kind { let res = cx.qpath_res(qp, fun.hir_id); return match res { def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true, def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id), _ => false, }; } } false } /// Returns `true` if a pattern is refutable. // TODO: should be implemented using rustc/mir_build/thir machinery pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool { fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool { matches!( cx.qpath_res(qpath, id), def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _) ) } fn are_refutable<'a, I: IntoIterator>>(cx: &LateContext<'_>, i: I) -> bool { i.into_iter().any(|pat| is_refutable(cx, pat)) } match pat.kind { PatKind::Wild => false, PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)), PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat), PatKind::Lit(..) | PatKind::Range(..) => true, PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id), PatKind::Or(pats) => { // TODO: should be the honest check, that pats is exhaustive set are_refutable(cx, pats) }, PatKind::Tuple(pats, _) => are_refutable(cx, pats), PatKind::Struct(ref qpath, fields, _) => { is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| field.pat)) }, PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats), PatKind::Slice(head, middle, tail) => { match &cx.typeck_results().node_type(pat.hir_id).kind() { rustc_ty::Slice(..) => { // [..] is the only irrefutable slice pattern. !head.is_empty() || middle.is_none() || !tail.is_empty() }, rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())), _ => { // unreachable!() true }, } }, } } /// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call /// the function once on the given pattern. pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) { if let PatKind::Or(pats) = pat.kind { pats.iter().for_each(f); } else { f(pat); } } pub fn is_self(slf: &Param<'_>) -> bool { if let PatKind::Binding(.., name, _) = slf.pat.kind { name.name == kw::SelfLower } else { false } } pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool { if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind { if let Res::SelfTy { .. } = path.res { return true; } } false } pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator> { (0..decl.inputs.len()).map(move |i| &body.params[i]) } /// Checks if a given expression is a match expression expanded from the `?` /// operator or the `try` macro. pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> { fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool { if_chain! { if let PatKind::TupleStruct(ref path, pat, None) = arm.pat.kind; if is_lang_ctor(cx, path, ResultOk); if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind; if path_to_local_id(arm.body, hir_id); then { return true; } } false } fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool { if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind { is_lang_ctor(cx, path, ResultErr) } else { false } } if let ExprKind::Match(_, arms, ref source) = expr.kind { // desugared from a `?` operator if *source == MatchSource::TryDesugar { return Some(expr); } if_chain! { if arms.len() == 2; if arms[0].guard.is_none(); if arms[1].guard.is_none(); if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) || (is_ok(cx, &arms[1]) && is_err(cx, &arms[0])); then { return Some(expr); } } } None } /// Returns `true` if the lint is allowed in the current context. This is useful for /// skipping long running code when it's unnecessary /// /// This function should check the lint level for the same node, that the lint will /// be emitted at. If the information is buffered to be emitted at a later point, please /// make sure to use `span_lint_hir` functions to emit the lint. This ensures that /// expectations at the checked nodes will be fulfilled. pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool { cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow } pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> { while let PatKind::Ref(subpat, _) = pat.kind { pat = subpat; } pat } pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 { Integer::from_int_ty(&tcx, ity).size().bits() } #[expect(clippy::cast_possible_wrap)] /// Turn a constant int byte representation into an i128 pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 { let amt = 128 - int_bits(tcx, ity); ((u as i128) << amt) >> amt } #[expect(clippy::cast_sign_loss)] /// clip unused bytes pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 { let amt = 128 - int_bits(tcx, ity); ((u as u128) << amt) >> amt } /// clip unused bytes pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 { let bits = Integer::from_uint_ty(&tcx, ity).size().bits(); let amt = 128 - bits; (u << amt) >> amt } pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool { attrs.iter().any(|attr| attr.has_name(symbol)) } pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool { let map = &tcx.hir(); let mut prev_enclosing_node = None; let mut enclosing_node = node; while Some(enclosing_node) != prev_enclosing_node { if has_attr(map.attrs(enclosing_node), symbol) { return true; } prev_enclosing_node = Some(enclosing_node); enclosing_node = map.local_def_id_to_hir_id(map.get_parent_item(enclosing_node)); } false } pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool { any_parent_has_attr(tcx, node, sym::automatically_derived) } /// Matches a function call with the given path and returns the arguments. /// /// Usage: /// /// ```rust,ignore /// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX); /// ``` pub fn match_function_call<'tcx>( cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, path: &[&str], ) -> Option<&'tcx [Expr<'tcx>]> { if_chain! { if let ExprKind::Call(fun, args) = expr.kind; if let ExprKind::Path(ref qpath) = fun.kind; if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id(); if match_def_path(cx, fun_def_id, path); then { return Some(args); } }; None } /// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if /// any. /// /// Please use `tcx.get_diagnostic_name` if the targets are all diagnostic items. pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option { let search_path = cx.get_def_path(did); paths .iter() .position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied())) } /// Checks if the given `DefId` matches the path. pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool { // We should probably move to Symbols in Clippy as well rather than interning every time. let path = cx.get_def_path(did); syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied()) } /// Checks if the given `DefId` matches the `libc` item. pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool { let path = cx.get_def_path(did); // libc is meant to be used as a flat list of names, but they're all actually defined in different // modules based on the target platform. Ignore everything but crate name and the item name. path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name) } /// Returns the list of condition expressions and the list of blocks in a /// sequence of `if/else`. /// E.g., this returns `([a, b], [c, d, e])` for the expression /// `if a { c } else if b { d } else { e }`. pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) { let mut conds = Vec::new(); let mut blocks: Vec<&Block<'_>> = Vec::new(); while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) { conds.push(cond); if let ExprKind::Block(block, _) = then.kind { blocks.push(block); } else { panic!("ExprKind::If node is not an ExprKind::Block"); } if let Some(else_expr) = r#else { expr = else_expr; } else { break; } } // final `else {..}` if !blocks.is_empty() { if let ExprKind::Block(block, _) = expr.kind { blocks.push(block); } } (conds, blocks) } /// Checks if the given function kind is an async function. pub fn is_async_fn(kind: FnKind<'_>) -> bool { matches!(kind, FnKind::ItemFn(_, _, header) if header.asyncness == IsAsync::Async) } /// Peels away all the compiler generated code surrounding the body of an async function, pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> { if let ExprKind::Call( _, &[ Expr { kind: ExprKind::Closure { body, .. }, .. }, ], ) = body.value.kind { if let ExprKind::Block( Block { stmts: [], expr: Some(Expr { kind: ExprKind::DropTemps(expr), .. }), .. }, _, ) = tcx.hir().body(body).value.kind { return Some(expr); } }; None } // check if expr is calling method or function with #[must_use] attribute pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { let did = match expr.kind { ExprKind::Call(path, _) => if_chain! { if let ExprKind::Path(ref qpath) = path.kind; if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id); then { Some(did) } else { None } }, ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id), _ => None, }; did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use)) } /// Checks if an expression represents the identity function /// Only examines closures and `std::convert::identity` pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { /// Checks if a function's body represents the identity function. Looks for bodies of the form: /// * `|x| x` /// * `|x| return x` /// * `|x| { return x }` /// * `|x| { return x; }` fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool { let id = if_chain! { if let [param] = func.params; if let PatKind::Binding(_, id, _, _) = param.pat.kind; then { id } else { return false; } }; let mut expr = &func.value; loop { match expr.kind { #[rustfmt::skip] ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, ) | ExprKind::Ret(Some(e)) => expr = e, #[rustfmt::skip] ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => { if_chain! { if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind; if let ExprKind::Ret(Some(ret_val)) = e.kind; then { expr = ret_val; } else { return false; } } }, _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(), } } } match expr.kind { ExprKind::Closure { body, .. } => is_body_identity_function(cx, cx.tcx.hir().body(body)), _ => path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, &paths::CONVERT_IDENTITY)), } } /// Gets the node where an expression is either used, or it's type is unified with another branch. /// Returns both the node and the `HirId` of the closest child node. pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> { let mut child_id = expr.hir_id; let mut iter = tcx.hir().parent_iter(child_id); loop { match iter.next() { None => break None, Some((id, Node::Block(_))) => child_id = id, Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id, Some((_, Node::Expr(expr))) => match expr.kind { ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id, ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id, ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None, _ => break Some((Node::Expr(expr), child_id)), }, Some((_, node)) => break Some((node, child_id)), } } } /// Checks if the result of an expression is used, or it's type is unified with another branch. pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool { !matches!( get_expr_use_or_unification_node(tcx, expr), None | Some(( Node::Stmt(Stmt { kind: StmtKind::Expr(_) | StmtKind::Semi(_) | StmtKind::Local(Local { pat: Pat { kind: PatKind::Wild, .. }, .. }), .. }), _ )) ) } /// Checks if the expression is the final expression returned from a block. pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool { matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..))) } pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> { if !is_no_std_crate(cx) { Some("std") } else if !is_no_core_crate(cx) { Some("core") } else { None } } pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool { cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| { if let ast::AttrKind::Normal(ref attr, _) = attr.kind { attr.path == sym::no_std } else { false } }) } pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool { cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| { if let ast::AttrKind::Normal(ref attr, _) = attr.kind { attr.path == sym::no_core } else { false } }) } /// Check if parent of a hir node is a trait implementation block. /// For example, `f` in /// ```rust /// # struct S; /// # trait Trait { fn f(); } /// impl Trait for S { /// fn f() {} /// } /// ``` pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool { if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) { matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. })) } else { false } } /// Check if it's even possible to satisfy the `where` clause for the item. /// /// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example: /// /// ```ignore /// fn foo() where i32: Iterator { /// for _ in 2i32 {} /// } /// ``` pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool { use rustc_trait_selection::traits; let predicates = cx .tcx .predicates_of(did) .predicates .iter() .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None }); traits::impossible_predicates( cx.tcx, traits::elaborate_predicates(cx.tcx, predicates) .map(|o| o.predicate) .collect::>(), ) } /// Returns the `DefId` of the callee if the given expression is a function or method call. pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option { match &expr.kind { ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id), ExprKind::Call( Expr { kind: ExprKind::Path(qpath), hir_id: path_hir_id, .. }, .., ) => { // Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or // deref to fn pointers, dyn Fn, impl Fn - #8850 if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, id) = cx.typeck_results().qpath_res(qpath, *path_hir_id) { Some(id) } else { None } }, _ => None, } } /// Returns Option where String is a textual representation of the type encapsulated in the /// slice iff the given expression is a slice of primitives (as defined in the /// `is_recursively_primitive_type` function) and None otherwise. pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option { let expr_type = cx.typeck_results().expr_ty_adjusted(expr); let expr_kind = expr_type.kind(); let is_primitive = match expr_kind { rustc_ty::Slice(element_type) => is_recursively_primitive_type(*element_type), rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => { if let rustc_ty::Slice(element_type) = inner_ty.kind() { is_recursively_primitive_type(*element_type) } else { unreachable!() } }, _ => false, }; if is_primitive { // if we have wrappers like Array, Slice or Tuple, print these // and get the type enclosed in the slice ref match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() { rustc_ty::Slice(..) => return Some("slice".into()), rustc_ty::Array(..) => return Some("array".into()), rustc_ty::Tuple(..) => return Some("tuple".into()), _ => { // is_recursively_primitive_type() should have taken care // of the rest and we can rely on the type that is found let refs_peeled = expr_type.peel_refs(); return Some(refs_peeled.walk().last().unwrap().to_string()); }, } } None } /// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)` /// `hash` must be comformed with `eq` pub fn search_same(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)> where Hash: Fn(&T) -> u64, Eq: Fn(&T, &T) -> bool, { match exprs { [a, b] if eq(a, b) => return vec![(a, b)], _ if exprs.len() <= 2 => return vec![], _ => {}, } let mut match_expr_list: Vec<(&T, &T)> = Vec::new(); let mut map: UnhashMap> = UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default()); for expr in exprs { match map.entry(hash(expr)) { Entry::Occupied(mut o) => { for o in o.get() { if eq(o, expr) { match_expr_list.push((o, expr)); } } o.get_mut().push(expr); }, Entry::Vacant(v) => { v.insert(vec![expr]); }, } } match_expr_list } /// Peels off all references on the pattern. Returns the underlying pattern and the number of /// references removed. pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) { fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) { if let PatKind::Ref(pat, _) = pat.kind { peel(pat, count + 1) } else { (pat, count) } } peel(pat, 0) } /// Peels of expressions while the given closure returns `Some`. pub fn peel_hir_expr_while<'tcx>( mut expr: &'tcx Expr<'tcx>, mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>, ) -> &'tcx Expr<'tcx> { while let Some(e) = f(expr) { expr = e; } expr } /// Peels off up to the given number of references on the expression. Returns the underlying /// expression and the number of references removed. pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) { let mut remaining = count; let e = peel_hir_expr_while(expr, |e| match e.kind { ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => { remaining -= 1; Some(e) }, _ => None, }); (e, count - remaining) } /// Peels off all references on the expression. Returns the underlying expression and the number of /// references removed. pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) { let mut count = 0; let e = peel_hir_expr_while(expr, |e| match e.kind { ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => { count += 1; Some(e) }, _ => None, }); (e, count) } /// Peels off all references on the type. Returns the underlying type and the number of references /// removed. pub fn peel_hir_ty_refs<'a>(mut ty: &'a hir::Ty<'a>) -> (&'a hir::Ty<'a>, usize) { let mut count = 0; loop { match &ty.kind { TyKind::Rptr(_, ref_ty) => { ty = ref_ty.ty; count += 1; }, _ => break (ty, count), } } } /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed. pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> { loop { match expr.kind { ExprKind::AddrOf(_, _, e) => expr = e, ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e, _ => break, } } expr } pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool { if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind { if let Res::Def(_, def_id) = path.res { return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr); } } false } static TEST_ITEM_NAMES_CACHE: OnceLock>>> = OnceLock::new(); fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool { let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default())); let mut map: MutexGuard<'_, FxHashMap>> = cache.lock().unwrap(); let value = map.entry(module); match value { Entry::Occupied(entry) => f(entry.get()), Entry::Vacant(entry) => { let mut names = Vec::new(); for id in tcx.hir().module_items(module) { if matches!(tcx.def_kind(id.def_id), DefKind::Const) && let item = tcx.hir().item(id) && let ItemKind::Const(ty, _body) = item.kind { if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind { // We could also check for the type name `test::TestDescAndFn` if let Res::Def(DefKind::Struct, _) = path.res { let has_test_marker = tcx .hir() .attrs(item.hir_id()) .iter() .any(|a| a.has_name(sym::rustc_test_marker)); if has_test_marker { names.push(item.ident.name); } } } } } names.sort_unstable(); f(entry.insert(names)) }, } } /// Checks if the function containing the given `HirId` is a `#[test]` function /// /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool { with_test_item_names(tcx, tcx.parent_module(id), |names| { tcx.hir() .parent_iter(id) // Since you can nest functions we need to collect all until we leave // function scope .any(|(_id, node)| { if let Node::Item(item) = node { if let ItemKind::Fn(_, _, _) = item.kind { // Note that we have sorted the item names in the visitor, // so the binary_search gets the same as `contains`, but faster. return names.binary_search(&item.ident.name).is_ok(); } } false }) }) } /// Checks if the item containing the given `HirId` has `#[cfg(test)]` attribute applied /// /// Note: Add `// compile-flags: --test` to UI tests with a `#[cfg(test)]` function pub fn is_in_cfg_test(tcx: TyCtxt<'_>, id: hir::HirId) -> bool { fn is_cfg_test(attr: &Attribute) -> bool { if attr.has_name(sym::cfg) && let Some(items) = attr.meta_item_list() && let [item] = &*items && item.has_name(sym::test) { true } else { false } } tcx.hir() .parent_iter(id) .flat_map(|(parent_id, _)| tcx.hir().attrs(parent_id)) .any(is_cfg_test) } /// Checks whether item either has `test` attribute applied, or /// is a module with `test` in its name. /// /// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool { is_in_test_function(tcx, item.hir_id()) || matches!(item.kind, ItemKind::Mod(..)) && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests") } /// Walks the HIR tree from the given expression, up to the node where the value produced by the /// expression is consumed. Calls the function for every node encountered this way until it returns /// `Some`. /// /// This allows walking through `if`, `match`, `break`, block expressions to find where the value /// produced by the expression is consumed. pub fn walk_to_expr_usage<'tcx, T>( cx: &LateContext<'tcx>, e: &Expr<'tcx>, mut f: impl FnMut(Node<'tcx>, HirId) -> Option, ) -> Option { let map = cx.tcx.hir(); let mut iter = map.parent_iter(e.hir_id); let mut child_id = e.hir_id; while let Some((parent_id, parent)) = iter.next() { if let Some(x) = f(parent, child_id) { return Some(x); } let parent = match parent { Node::Expr(e) => e, Node::Block(Block { expr: Some(body), .. }) | Node::Arm(Arm { body, .. }) if body.hir_id == child_id => { child_id = parent_id; continue; }, Node::Arm(a) if a.body.hir_id == child_id => { child_id = parent_id; continue; }, _ => return None, }; match parent.kind { ExprKind::If(child, ..) | ExprKind::Match(child, ..) if child.hir_id != child_id => child_id = parent_id, ExprKind::Break(Destination { target_id: Ok(id), .. }, _) => { child_id = id; iter = map.parent_iter(id); }, ExprKind::Block(..) => child_id = parent_id, _ => return None, } } None } macro_rules! op_utils { ($($name:ident $assign:ident)*) => { /// Binary operation traits like `LangItem::Add` pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*]; /// Operator-Assign traits like `LangItem::AddAssign` pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*]; /// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> { match kind { $(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)* _ => None, } } }; } op_utils! { Add AddAssign Sub SubAssign Mul MulAssign Div DivAssign Rem RemAssign BitXor BitXorAssign BitAnd BitAndAssign BitOr BitOrAssign Shl ShlAssign Shr ShrAssign }